Disinfection with ultraviolet (UV) light can dramatically increase the storage and shelf life of many manufactured products. Extending shelflife by a safe and relatively inexpensive process allows the manufacturers of these products to reduce the use of chemical preservatives and disinfectants. UV light disinfection systems offer the advantage of lower operation costs as compared with conventional chemical additives and cleaning agents. UV light disinfection systems are utilized in many industries as an environmentally safe and regulation free method of sterilization. Additionally, UV disinfection systems are free from consumer or environmental concerns that are often voiced regarding conventional chemical disinfection methods. UV disinfection systems have been used successfully in many drinking and process water applications, and in hospitals, pharmaceutical and beverage production.
Bacteria, molds and viruses substantially absorb UV wavelengths of 210 nm and 310 nm. It is understood that this absorbed UV radiation adversely affects the survivability of many pathogens, such as bacteria, molds and viruses. Standard, commercially available UV lamps can efficiently emit a broad germicidal spectrum that includes these specific wavelengths of UV light, and in the intensity required for effective control. A UV dose of approximately 0.1 joules/cm.sup.2 is considered effective in controlling these pathogens. Disinfection is a term that is typically employed to describe the elimination of substantially all pathogens with very few survivors, while the term sterilization is employed to describe the total elimination of all pathogens, without any survivors.
UV light has also been utilized to disinfect the surfaces of packages. A wrapped or enveloped product is subjected to a UV light source to control potential contamination on the surface of the packaging. Conventional packaging lines equipped with surface UV disinfection equipment often include a photoelectric interlock. The photoelectric interlock includes a photoelectric sensor that detects the presence of a package or carton in proximity to the UV lamp on a process line. The UV lamp is mounted to a fixed frame, typically above the process line. When enabled by the photo electric interlock, the UV lamp illuminates the package as it passes beneath and so sterilizes the top facing surfaces of the package.
A problem occurs when the package has surfaces that require disinfection but these surfaces do not face the UV lamp as the package passes the UV lamp. Additional passes under the UV lamp must be made to illuminate the other surfaces of the package. This single surface disinfection may be acceptable for flat, roughly two sided packaging, but is typically not acceptable for multi-sided packages.
An additional problem occurs if it is desired to sterilize containers of various sizes. In practice, the process line is configured to handle only one size of a container. The process line must be shut down and reconfigured to compensate for any change in distance from the UV lamp to the carton.
Produce products, such as fruits and vegetables, are washed and typically scrubbed before packing into boxes. Typically, clean, sterilized or at least substantially disinfected water must be utilized to wash the produce product to minimize the introduction of molds and bacteria onto the produce product. Ultraviolet light treatment of the wash water is employed to provide assurance that the wash water is pure and clean.
Additionally, when brushes are used to scrub, dry or polish the produce product, the brushes themselves can become contaminated with molds or bacteria and serve to spread the contamination to much of the produce that passes through the brushes. This problem makes storing the packed fruit difficult, because a single contaminated piece of produce product can ruin an entire box of packed produce in a short period. A method and apparatus that cleans produce products without the use of water as a final cleaning and disinfecting step is needed.